pve-network.adoc

   1 Network Configuration
   2 ---------------------
   3 include::attributes.txt[]
   4
   5 {pve} uses a bridged networking model. Each host can have up to 4094
   6 bridges. Bridges are like physical network switches implemented in
   7 software. All VMs can share a single bridge, as if
   8 virtual network cables from each guest were all plugged into the same
   9 switch. But you can also create multiple bridges to separate network
  10 domains.
  11
  12 For connecting VMs to the outside world, bridges are attached to
  13 physical network cards. For further flexibility, you can configure
  14 VLANs (IEEE 802.1q) and network bonding, also known as "link
  15 aggregation". That way it is possible to build complex and flexible
  16 virtual networks.
  17
  18 Debian traditionally uses the `ifup` and `ifdown` commands to
  19 configure the network. The file `/etc/network/interfaces` contains the
  20 whole network setup. Please refer to to manual page (`man interfaces`)
  21 for a complete format description.
  22
  23 NOTE: {pve} does not write changes directly to
  24 `/etc/network/interfaces`. Instead, we write into a temporary file
  25 called `/etc/network/interfaces.new`, and commit those changes when
  26 you reboot the node.
  27
  28 It is worth mentioning that you can directly edit the configuration
  29 file. All {pve} tools tries hard to keep such direct user
  30 modifications. Using the GUI is still preferable, because it
  31 protect you from errors.
  32
  33
  34 Naming Conventions
  35 ~~~~~~~~~~~~~~~~~~
  36
  37 We currently use the following naming conventions for device names:
  38
  39 * Ethernet devices: eth[N], where 0 ≤ N (`eth0`, `eth1`, ...)
  40
  41 * Bridge names: vmbr[N], where 0 ≤ N ≤ 4094 (`vmbr0` - `vmbr4094`)
  42
  43 * Bonds: bond[N], where 0 ≤ N (`bond0`, `bond1`, ...)
  44
  45 * VLANs: Simply add the VLAN number to the device name,
  46   separated by a period (`eth0.50`, `bond1.30`)
  47
  48 This makes it easier to debug networks problems, because the device
  49 names implies the device type.
  50
  51 Default Configuration using a Bridge
  52 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  53
  54 The installation program creates a single bridge named `vmbr0`, which
  55 is connected to the first ethernet card `eth0`. The corresponding
  56 configuration in `/etc/network/interfaces` looks like this:
  57
  58 ----
  59 auto lo
  60 iface lo inet loopback
  61
  62 iface eth0 inet manual
  63
  64 auto vmbr0
  65 iface vmbr0 inet static
  66         address 192.168.10.2
  67         netmask 255.255.255.0
  68         gateway 192.168.10.1
  69         bridge_ports eth0
  70         bridge_stp off
  71         bridge_fd 0
  72 ----
  73
  74 Virtual machines behave as if they were directly connected to the
  75 physical network. The network, in turn, sees each virtual machine as
  76 having its own MAC, even though there is only one network cable
  77 connecting all of these VMs to the network.
  78
  79
  80 Routed Configuration
  81 ~~~~~~~~~~~~~~~~~~~~
  82
  83 Most hosting providers do not support the above setup. For security
  84 reasons, they disable networking as soon as they detect multiple MAC
  85 addresses on a single interface.
  86
  87 TIP: Some providers allows you to register additional MACs on there
  88 management interface. This avoids the problem, but is clumsy to
  89 configure because you need to register a MAC for each of your VMs.
  90
  91 You can avoid the problem by ``routing'' all traffic via a single
  92 interface. This makes sure that all network packets use the same MAC
  93 address.
  94
  95 A common scenario is that you have a public IP (assume `192.168.10.2`
  96 for this example), and an additional IP block for your VMs
  97 (`10.10.10.1/255.255.255.0`). We recommend the following setup for such
  98 situations:
  99
 100 ----
 101 auto lo
 102 iface lo inet loopback
 103
 104 auto eth0
 105 iface eth0 inet static
 106         address  192.168.10.2
 107         netmask  255.255.255.0
 108         gateway  192.168.10.1
 109         post-up echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp
 110
 111
 112 auto vmbr0
 113 iface vmbr0 inet static
 114         address  10.10.10.1
 115         netmask  255.255.255.0
 116         bridge_ports none
 117         bridge_stp off
 118         bridge_fd 0
 119 ----
 120
 121
 122 Masquerading (NAT) with `iptables`
 123 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 124
 125 In some cases you may want to use private IPs behind your Proxmox
 126 host's true IP, and masquerade the traffic using NAT:
 127
 128 ----
 129 auto lo
 130 iface lo inet loopback
 131
 132 auto eth0
 133 #real IP adress
 134 iface eth0 inet static
 135         address  192.168.10.2
 136         netmask  255.255.255.0
 137         gateway  192.168.10.1
 138
 139 auto vmbr0
 140 #private sub network
 141 iface vmbr0 inet static
 142         address  10.10.10.1
 143         netmask  255.255.255.0
 144         bridge_ports none
 145         bridge_stp off
 146         bridge_fd 0
 147
 148         post-up echo 1 > /proc/sys/net/ipv4/ip_forward
 149         post-up   iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o eth0 -j MASQUERADE
 150         post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o eth0 -j MASQUERADE
 151 ----
 152
 153 ////
 154 TODO: explain IPv6 support?
 155 TODO: explan OVS
 156 ////